Zoom lens and image pick-up apparatus

ABSTRACT

A zoom lens including a broad picture angle of 60 to 100 degrees as a photographic picture angle of the wide-angle end state, and having a magnification ratio of about three to six times, small front gem diameter, excellent compactness and high image formation performance, which is used in a video camera or a digital still camera, and an image pick-up apparatus using such a zoom lens. A zoom lens ( 20 ), consisting of plural groups and serving to change group spacing or spacings to thereby perform a magnification changing or adjusting operation, comprises a first lens group GR 1  having positive refractive power, a second lens group GR 2  having negative refractive power and a third lens group GR 3  having positive refractive power which are arranged in order from the object side, and a last group GRR arranged at the side closest to the image surface and having negative refractive power, wherein the first lens group GR 1  is constituted by single positive lens G 1 , and satisfies the following conditional formulas.
 
0.5&lt; Y max/ FW &lt;1.3  (1)
 
VdG1&gt;40  (2)
 
In the above formula,
         Ymax: maximum image height on image pick-up surface;   FW: focal length at the wide-angle end state of the lens entire; and system   VdG1: Abbe number at d line of the first lens group GR 1.

TECHNICAL FIELD

The present invention relates to a novel zoom lens and a novel imagepick-up apparatus. More particularly, the present invention relates to azoom lens including a broad picture angle of 60 to 100 degrees as aphotographic picture angle of the wide-angle end state, having amagnification ratio of about 3 to 6 times, small optical gem diameter,excellent compactness and high image formation performance, which issuitable for a photographic optical system of digital input/outputequipment such as a digital still camera or a digital video camera,etc.; and an image pick-up apparatus comprising such a zoom lens.

This Application claims priority of Japanese Patent Application No.2005-068932, field on Mar. 11, 2005, the entirety of which isincorporated by reference herein.

BACKGROUND ART

In recent years, image pick-up apparatuses using a solid-state imagepick-up device such as a digital still camera are being popularized.Further, with popularization of digital still cameras, there is requireda zoom lens having excellent compactness and having high image formationperformance, while covering the range from a super-broad angle side upto the telescopic side by a single lens.

For example, in the zoom lens described in the Japanese PatentApplication Laid Open No. 1995-261084 publication, a zoom lensconfiguration including a negative lens group as a preceding lens groupis used to realize a broad angle of the zoom lens. However, in the zoomlens described in the Japanese Patent Application Laid Open No.1995-261084 publication, the magnification ratio is small. Themagnification of about two times or three times is a limit. Realizationof high magnification is difficult.

On the other hand, in the zoom lenses described in the Japanese PatentApplication No. 1997-5629 publication, and the Japanese PatentApplication No. 1995-318805 publication, the zoom configurationincluding a positive lens group as the preceding lens group is used torealize high magnification of the zoom lens and broad angle thereof.

However, in the Japanese Patent Application Laid Open No. 1997-5629publication and the Japanese Patent Application Laid Open No.1995-318805 publication, a photographic picture angle of about 80degrees is a limit. As a result, realization of a broader angle isdifficult. Moreover, even if realization of a broader angle can beattained, the number of lenses constituting the first lens group havinga large lens diameter is increased so that miniaturization is notsufficient, cost is increased and weight also becomes heavy. This is notpreferable.

In view of the above, an object of the present invention is to provide azoom lens including a broad picture angle of 60 to 100 degrees as aphotographic picture angle of a wide-angle end state, and having amagnification ratio of about three to six times, small front optical gemdiameter and excellent compactness, and high image formationperformance, which is used in video camera or digital still camera; andan image pick-up apparatus comprising such zoom lens.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

In order to solve the above-described problems, the zoom lens of thepresent invention consists of plural groups and serving to change groupspacing or spacings to thereby perform a magnification changing oradjusting operation, and comprises a first lens group GR1 havingpositive refractive power, a second lens group GR2 having negativerefractive power, a third lens group GR3 having positive refractivepower which are arranged in order from the object side, and a last lensgroup GRR arranged at the side closest to the image surface and havingnegative refractive power, wherein the first lens group GR1 isconstituted by single positive lens. When Ymax indicates the maximumimage height on the image pick-up surface, FW indicates a focal lengthat the wide-angle end state of the lens entire system, and VdG1indicates Abbe number at d line of the first lens group GR1, thefollowing conditional formulas are satisfied.0.5<Ymax/FW<1.3,  (1)VdG1>40.  (2)

Moreover, in order to solve the above-mentioned problems, the imagepick-up apparatus of the present invention comprises a zoom lensconsisting of plural groups and serving to change group spacing orspacings to thereby perform a magnification changing or adjustingoperation, and an image pick-up device for converting an optical imageformed by the zoom lens into an electric signal, the zoom lenscomprising a first lens group GR1 having positive refractive power, asecond lens group GR2 having negative refractive power and a third lensgroup GR3 having positive refractive power which are arranged in orderfrom the object side, and a last lens group GRR arranged at the sideclosest to the image surface and having negative refractive power,wherein the first lens group GR1 is constituted by a single positivelens, and when Ymax indicates the maximum image height on the imagepick-up surface, FW indicates focal length at the wide-angle end stateof the lens entire system, and VdG1 indicates Abbe number at d line ofthe first lens group GR1, the conditional formulas (1) 0.5<Ymax/FW<1.3and (2) VdG1>40 are satisfied.

Accordingly, in the zoom lens of the present invention, a photographicpicture angle at the wide-angle end state includes a broad picture angleof 60 to 100 degrees, the magnification ratio is about three to sixtimes, the front gem diameter is small, compactness is excellent, andhigh image formation performance is provided. Moreover, since the imagepick-up apparatus of the present invention comprises a zoom lens of thepresent invention, a photographing operation having a broad pictureangle about of 60 to 100 degrees can be performed. Thus, a photographingoperation by an arbitrary picture angle within a magnification ratio ofthree times to six times can be performed, and an image of high qualitycan be acquired by high performance image formation performance.

Accordingly, in the zoom lens of the present invention, it is possibleto attain a magnification ratio of about three times to six times whileincluding a broad picture angle of 60 to 100 degrees as a photographicpicture angle of the wide-angle end state. Moreover, since an image ismagnified or enlarged by the last lens group, the front gem of the firstlens group GR1 can be constituted as a small-sized front gem. Inaddition, since a height of rays of marginal (peripheral) light passedthrough the first lens group GR1 at the telescopic end state can belower than that of the ordinary zoom lens, the first lens group GR1which has the greatest influence on axial color aberration can beconstituted only by single lens. Thus, it is possible to attainminiaturization and/or light weight of the lens entire system whilemaintaining a picture angle of 60 to 100 degrees and a magnificationratio of about three times to six times.

Moreover, since the image pick-up of the present invention comprises thezoom lens of the present invention, a photographing operation having thebroad picture angle of about 60 to 100 degrees can be performed althoughthe image pick-up apparatus is small-sized and light in weight. As aresult, a photographing operation by an arbitrary picture angle withinthe magnification ratio of three to six times can be performed. Inaddition, image of high quality can be acquired by high image formationperformance.

In the inventions described in one aspect, since the first lens groupGR1 satisfies the conditional formula (3) 2<F1/√FW·FT<15 when F1 is afocal length of the first lens group GR1, FT is a focal length at thetelescopic end state of the lens entire system, and √FW·FT is the squareroot of a product of FW and FT, various aberrations including sphericalaberration can be further satisfactorily corrected, and furtherminiaturization/light weight can be made.

In the inventions described in the another aspect, since the last lensgroup GRR includes a negative lens GRn at the side closest to the objectand a positive lens GRp at the side closest to the image surface, andsatisfies the conditional formulas (4) 1.2<βGRRT<1.8, (5)0.2<Twbf/FW<1.2 and (6) VdGRRn>VdGRRp when βGRRT is the magnification atthe telescopic end state of the last lens group GRR, Twbf is back focus(i.e., air conversion length) at the wide-angle end state, VdGRRn is theAbbe number at a d line of the negative lens GRn and VdGRRp is the Abbenumber at a d line of the positive lens GRp, marginal rays of light arejumped upwards by the negative lens located at the side closest to theobject side and are suppressed by the positive lens located at the sideclosest to the image surface at the last lens group GRR to therebypermit an incident angle onto the image pick-up device to be gentle orsmall, and to realize a high performance by miniaturization, highmagnification and color aberration reduction. Moreover, at thewide-angle end state, the lens GRn at the side closest to the object andthe lens GRp at the side closest to the object surface in the lens atthe side closest to the object (constituting the first lens group GR1),the lens at the side closest to the object of the second lens group GR2and the last lens group GRR has symmetry in the lens configuration,i.e., the relationship of positive, negative: negative, positive with anaperture diaphragm being put therebetween, thus making it possible tosuppress distortion aberration while realizing broad angle.

In the inventions described in still another aspect, since at least onelens surface of the second lens group GR2 is constituted by anon-spherical surface, and the second lens group GR2 satisfies theconditional formula (7) 0.4<|F2/√FW·FT|<1.0 when F2 is a focal length ofthe second lens group GR2, chromatic aberration in the radial directionat the wide-angle end state can be effectively corrected, andminiaturization and realization of high performance can be attained atthe same time.

In the inventions described in yet another feature, since the third lensgroup GR3 at least includes one positive lens and one negative lens, atleast one lens plane surface is constituted by a non-spherical surface,and the third lens group GR3 satisfies the conditional formula (8) VdGR3p>50 when VdGR3 p is an average value of Abbe numbers at a d line of thepositive lens within the third lens group GR3, it is possible tosuppress occurrence of color aberration to maintain high opticalperformance over the entire range. In addition, at least one lens planesurface is constituted by a non-spherical surface to thereby suppressoccurrence of various aberrations such as spherical aberration and/orchromatic aberration, etc., thus making it possible to maintain highoptical performance over the zooming range.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing lens configuration of a first embodiment of azoom lens of the present invention.

FIG. 2 shows, together with FIGS. 3 and 4, various aberration diagramsof a numerical value embodiment 1 in which practical numerical valuesare applied to the first embodiment of the zoom lens of the presentinvention, and this Figure shows spherical aberration, astigmatism anddistortion aberration at the wide-angle end state.

FIG. 3 shows spherical aberration, astigmatism and distortion aberrationat intermediate focal length.

FIG. 4 shows spherical aberration, astigmatism and distortion aberrationat the telescopic end state.

FIG. 5 is a view showing lens configuration of a second embodiment ofthe zoom lens of the present invention.

FIG. 6 shows, together with FIGS. 7 and 8, various aberration diagramsof a numerical value embodiment 2 in which practical numerical valuesare applied to a second embodiment of a zoom lens of the presentinvention, and this Figure shows spherical aberration, astigmatism anddistortion aberration at the wide-angle end state.

FIG. 7 shows spherical aberration, astigmatism and distortion aberrationat the intermediate focal length.

FIG. 8 shows spherical aberration, astigmatism and distortion aberrationat the telescopic end state.

FIG. 9 is a view showing the lens configuration of a third embodiment ofthe zoom lens of the present invention.

FIG. 10 shows, together with FIGS. 11 and 12, various aberrationdiagrams of a numerical value embodiment 3 in which practical numericalvalues are applied to the third embodiment of the zoom lens of thepresent invention, and this Figure shows spherical aberration,astigmatism and distortion aberration at the wide-angle end state.

FIG. 11 shows spherical aberration, astigmatism and distortionaberration at the intermediate focal length.

FIG. 12 shows spherical aberration, astigmatism and distortionaberration at the telescopic end state.

FIG. 13 is a view showing the lens configuration of a fourth embodimentof the zoom lens of the present invention.

FIG. 14 shows, along with FIGS. 15 and 16, various aberration diagramsof a numerical value embodiment 4 in which practical numerical valuesare applied to the fourth embodiment of the zoom lens of the presentinvention, and this Figure shows spherical aberration, astigmatism anddistortion aberration at the wide-angle end state.

FIG. 15 shows spherical aberration, astigmatism and distortionaberration at the intermediate focal length.

FIG. 16 shows spherical aberration, astigmatism and distortionaberration at the telescopic end state.

FIG. 17 is a block diagram showing an embodiment of an image pick-upapparatus of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Best mode for carrying out the zoom lens and image pick-up apparatus ofthe present invention will now be explained with reference to theattached drawings.

The zoom lens of the present invention is directed to a zoom lensconsisting of plural groups and serving to change group spacing orspacings to thereby perform a magnification changing or adjustingoperation, and comprises a first lens group GR1 having positiverefractive power, a second lens group GR2 having negative refractivepower and a third lens group GR3 having positive refractive power whichare arranged in order from the object side, and a last lens group GRRarranged at the side closest to the image surface and having negativerefractive power, wherein the first lens group GR1 is constituted by asingle positive lens, and satisfies the following conditional formulas(1), (2).0.5<Ymax/FW<1.3  (1)VdG1>40  (2)In the above formula,

-   -   Ymax: maximum image height on an image pick-up surface    -   FW: focal length at the wide-angle end state of the entire lens        system; and    -   VdG1: Abbe number at a d line of the first lens group GR1

Accordingly, in the zoom lens of the present invention, it is possibleto attain a magnification ratio of about three times to six times whileincluding a broad picture angle of 60 to 100 degrees as a photographicpicture angle of the wide-angle end state. Moreover, since the image ismagnified or enlarged by the last lens group GRR, the front optical gemdiameter of the first lens group GR1 can be constituted as aminiaturized configuration, and a height of the marginal (i.e.,peripheral) rays of light passed through the first lens group GR1serving as a positive lens group at the telescopic end state can bereduced as compared to the ordinary zoom lens. For this reason, thefirst lens group GR1 which has the greatest influence on the axial coloraberration can be constituted by only a single positive lens. Further,miniaturization and light weight of the lens entire system can beattained while maintaining a picture angle of 60 to 100 degrees, and amagnification ratio of about three times to six times.

The conditional formula (1) prescribes a ratio between the maximum imageheight on the image pick-up surface and the focal length at thewide-angle end state of the entire lens system.

When the value of Ymax/FW is 0.5 or less, i.e., there results atelescopic state, a positive power of the first lens group GR1 becomestoo strong. As a result, the influence of axial color aberration at thetelescopic side becomes too strong so that correction cannot be madeonly by single lens. Moreover, when the value of Ymax/FW is 1.3 or more,i.e., there results a broad angle state, and a positive power of thefirst lens group GR1 becomes too weak. As a result, the effectivediameter of the first lens group GR1 becomes large so thatminiaturization and light weight become difficult.

Preferably, it is desirable to satisfy the range of 0.8<Ymax/FW<1.20.

The conditional formula (2) prescribes occurrence quantity of coloraberrations of the first lens group serving as positive single lens. Inthe case where VdG1 is 40 or less, the influence of the axial coloraberration at the telescopic side becomes too great. Correction of thisphenomenon becomes difficult also at the entirety of the lens system.Preferably, it is desirable to satisfy the range of VdG1>55.

It is desirable that the first lens group GR1 satisfies the followingconditional formula (3).2<F1/√FW·FT<15  (3)In the above formula,

-   -   F1: focal length of the first lens group GR1;    -   FT: focal length at the telescopic end state of the entire lens        system; and    -   √FW·FT: square root of the product of FW and FT.

The conditional formula (3) prescribes a ratio between the focal lengthof the first lens group GR1 having a positive refractive powerconstituted by a positive single lens and the focal length of theintermediate area in the entire lens system. In the case where F1/√FW·FTis 2 or less, the refractive power of the first lens group GR1 becomestoo strong. As a result, the influence of various aberrations includingspherical aberration becomes large. Correction of such phenomenonbecomes difficult even at the entire lens system. Moreover, in the casewhere F1/√FW·FT is 15 or more, the refractive power of the first lensgroup GR1 becomes too weak. As a result, realization of a highmagnification becomes difficult, and miniaturization/light weight alsobecome difficult.

It is desirable that the last lens group GRR includes a negative lensGRn at the side closest to the object, and a positive lens GRp at theside closest to the image surface, and satisfies the followingconditional formulas (4), (5) and (6).1.2<βGRRT<1.8  (4)0.2<Twbf/FW<1.2  (5)VdGRRn>VdGRRp  (6)In the above formula,

-   -   βGRRT: magnification at the telescopic end state of the last        lens group GRR;    -   Twbf: back focus (i.e., air conversion length) at the wide-angle        end state;    -   VdGRRn: Abbe number at a d line of the negative lens GRn; and    -   VdGRRp: Abbe number at a d line of the positive lens GRp.

The last lens group GRR includes negative lens GRn at a side closest tothe object and a positive lens GRp at the side closest to the imagesurface to thereby jump upward marginal rays of light by the negativelens GRn and to suppress them by the positive lens GRp, thus permittingan incident angle onto the image pick-up device of marginal rays oflight to be gentle or small. Moreover, at the wide-angle end state, thelens GRn at the side closest to the object and the lens GRp at the sideclosest to the image surface in the lens at the side closest to theobject (constituting the first lens group GR1), the lens at the sideclosest to the second lens group GR2 and the last lens group GRR havesymmetry in the lens configuration, i.e., the relationship of positive,negative: negative, positive with aperture diaphragm being puttherebetween, thus to have an ability to suppress a distortionaberration while performing a realization of a broad angle.

The conditional formula (4) prescribes magnification at the telescopicend state of the last lens group GRR. In the case where βGRRT is 1.2 orless, magnification by the last lens group GRR is reduced. As a result,not only the first lens group serving as the front optical gem isenlarged, but also a height of rays of light passed through the firstlens group GR1 at the telescopic end state also becomes high. Thus, theinfluence of axial color aberration and/or spherical aberration, etc.become large so that it becomes impossible to maintain the performanceonly by a single lens. On the other hand, in the case where βGRRT is 1.8or more, magnification by the last lens group GRR becomes large.Although it is advantageous to miniaturization/light weight, variousaberrations left at the lens groups before the last lens group GRR wouldbe increased. As a result, realization of high performance andassembling accuracy also becomes rigorous.

The conditional formula (5) prescribes a ratio between BF (back focus)length at the wide-angle end state and focal length of the lens entiresystem at the wide-angle end state. Namely, in the case where the valueof Twbf/FW is 0.2 or less, a LPF (Low-Pass Filter) and/or IR (Infrared)cut glass becomes extremely close to the image pick-up surface. As aresult, a defect of the LPF or the IR cut glass and/or dust attachedthereto are apt to become conspicuous at the time of minimum iris.Moreover, in the case where value of Twbf/FW is 1.2 or more, the lensfront gem becomes large. As a result, not only miniaturization becomesdifficult, but also realization of broad angle becomes difficult.

The conditional formula (6) prescribes an occurrence quantity of coloraberrations of the last lens group GRR. When this condition is notsatisfied, the occurrence quantity of magnification color aberrations atthe last group becomes large. Correction of such occurrence quantitybecomes difficult even at the lens entire system.

It is desirable that at least one lens surface of the second lens groupGR2 is constituted by a non-spherical surface, and the second lens groupGR2 satisfies the following conditional formula (7).0.4<|F2/√FW·FT|<1.0  (7)In the above formula,

F2: focal length of the second lens group GR2.

The second lens group GR2 is caused to have at least one non-sphericalsurface to thereby have ability to effectively correct chromaticaberration in the radial direction at the wide-angle end state. Thus,miniaturization and high performance can be attained at the same time.

The conditional formula (7) prescribes ratio between a focal length ofthe second lens group GR2 having a negative refractive power and a focallength within the intermediate area in the lens entire system. In thecase where F2/√FW·FT is 0.4 or less, the refractive power of the secondlens group GR2 becomes too strong. Thus, a correction of image surfacebending or curvature or marginal chromatic aberration becomes difficult.Moreover, in the case where F1/√FW·FT is 1.0 or more, the refractivepower of the second lens group GR2 becomes too weak. As a result, arealization of high magnification becomes difficult, or the movablerange of the second lens group GR2 for the purpose of obtaining apredetermined magnification becomes large so that miniaturization wouldbecome difficult.

It is desirable that the third lens group GR3 has at least one positivelens and one negative lens, and at least one lens plane surface ofrespective lens planes or plane surfaces is constituted by anon-spherical surface and the third lens group GR3 satisfies thefollowing conditional formula (8).VdGR3p>50  (8)In the above formula,

-   -   VdGR3 p: average value of Abbe numbers at a d line of the        positive lens within the third lens group GR3

Thus, occurrence of a color aberration is suppressed thus to haveability to maintain high optical performance over the entire range.Moreover, at least one plane or plane surface of a lens respective planesurfaces constituting the third lens group GR3 is constituted bynon-spherical surface. Thus, an occurrence of various aberrations suchas spherical aberration or chromatic aberration, etc. are suppressedthus to have ability to maintain high optical performance over theentire zooming range.

It is desirable that at least one plane or plane surface of respectiveplanes of lenses constituting the last lens group GRR is constituted bynon-spherical surface. This is because it is thus possible toeffectively correct distortion aberration or image surface bending orcurvature at the peripheral area.

In addition, it is most desirable that the zoom lens of the presentinvention has a magnification ratio of about four times five times inorder to simultaneously attain realization of broad angle andcompactness.

Four embodiments of the zoom lens of the present invention and numericvalue embodiments in which practical numeric values are applied to theseembodiments will now be explained with reference to FIGS. 1 to 16 andTables 1 to 13.

It is to be noted that while a non-spherical surface is used in therespective embodiments, the non-spherical shape is represented by thefollowing formula (1).

$\begin{matrix}\text{[Formula~~1]} & \; \\{x = {\frac{y^{2} \cdot c^{2}}{1 + ( {1 - {( {1 + K} ) \cdot y^{2} \cdot c^{2}}} )^{1/2}} + {\sum{A^{i} \cdot y^{i}}}}} & (1)\end{matrix}$In the above formula,

-   -   y: height in a direction perpendicular to the optical axis;    -   x: distance in the optical axis direction from lens plane        surface summit point;    -   c: paraxial curvature at lens summit point;    -   k: conic constant; and    -   A^(i): the i-th non-spherical coefficient.

FIG. 1 shows the lens configuration by the first embodiment 1 of thezoom lens system of the present invention, wherein there are arranged,in order from the object side, a first lens group GR1 having positiverefractive power, a second lens group GR2 having negative refractivepower, a third lens group GR3 having positive refractive power, a fourthlens group GR4 having positive refractive power, a fifth lens group GR5having negative refractive power, and a sixth lens group GR6 havingnegative refractive power. Further, in a magnification changing oradjusting operation from the wide-angle end state up to the telescopicend state, respective lens groups are moved on the optical axis asindicated by arrowed of solid lines in FIG. 1.

The first lens group GR1 is comprised of a single lens G11 havingpositive refractive power. The second lens group GR2 is composed of anegative lens G12 having composite non-spherical surface at the objectside, a negative lens G13, and a positive lens G14. The third lens groupGR3 is composed of a positive lens G15 having non-spherical surfaces atboth surface sides, an iris S, and a negative lens G16. The fourth lensgroup GR4 is comprised of a connection lens of a positive lens G17 and anegative lens G18. The fifth lens group GR5 is comprised of a negativelens G19 having a non-spherical surface at the object side. The sixthlens group GR6 is composed of a negative lens G110, a positive lensG111, and a positive lens G112.

Moreover, in the first embodiment and the second, third and fourthembodiments which will be described later, a parallel plane surfaceplate-shaped low-pass filter LPF is disposed between the last lens planesurface and the image pick-up surface IMG. It is to be noted that, asthe above-mentioned low-pass filter LPF, there may be applied a doublerefraction type low-pass filter using, as material, quartz, etc. inwhich a crystallization axis is adjusted in a predetermined direction,and/or a phase type low-pass filter for attaining a required opticalcut-off frequency characteristic by a diffraction effect.

Values of various elements of a numerical value embodiment 1 in whichpractical numerical values are applied to the first embodiment are shownin Table 1. The plane No. in various element Tables of the numericalvalue embodiment 1 and respective numerical value embodiments which willbe explained later indicates the i-th plane from the object side, Rindicates a radius of curvature of the i-th plane, D indicates an axialspacing between the i-th plane and the (i+1)-th plane, Nd indicates arefractive index with respect to a d line (λ=587.6 nm) of nitricmaterial having the i-th plane at the body side, and Vd indicates Abbenumber with respect to a d line of nitric material having the i-th planeat the object side. Moreover, a plane indicated by “ASP” indicates anon-spherical surface. Radius of curvature “INFINITY” indicates a plane.

TABLE 1 PLANE No. R D Nd Vd  1 79.293 5.384 1.4875 70.441  2 22777.974variable  3 606.965 ASP 0.200 1.5361 41.200  4 147.526 1.500 1.835042.984  5 19.773 7.766  6 47107.787 1.100 1.8350 42.984  7 34.902 3.657 8 49.228 3.258 1.9229 20.884  9 805.396 variable 10 16.118 ASP 4.1571.5831 59.460 11 −62.255 ASP 3.443 IRIS INFINITY 3.000 13 28.928 0.9001.9229 20.884 14 14.588 variable 15 25.650 4.511 1.4970 81.608 16−10.988 0.900 1.7292 54.674 17 −19.579 variable 18 −199.771 ASP 1.6001.5831 59.460 19 184.409 variable 20 −12.900 1.000 1.8340 37.345 2189.461 0.703 22 1121.947 3.379 1.5814 40.888 23 −23.344 0.200 24 50.3172.956 1.9229 20.884 25 −147.936 variable 26 INFINITY 1.200 1.5168 64.19827 INFINITY 1.620 1.5523 63.424 28 INFINITY 1.000 29 INFINITY 0.5001.5567 58.649 30 INFINITY 1.000 i INFINITY 0.000

In accordance with change of the lens position state from the broadangle end state up to the telescopic end state, a spacing D2 between thefirst lens group GR1 and the second lens group GR2, spacing D9 betweenthe second lens group GR2 and the third lens group GR3, spacing D14between the third lens group GR3 and the fourth lens group GR4, spacingD17 between the fourth lens group GR4 and the fifth lens group GR5,spacing D19 between the fifth lens group GR5 and the sixth lens groupGR6, and spacing D25 between the sixth lens group GR6 and the low-passfilter LPF are changed. In view of the above, various values at thewide-angle end state of the respective spacings, an intermediate focallength between the wide-angle end state and the telescopic end state,and the telescopic end state are shown in Table 1 along with focallength f, F number Fno. and half picture angle ω.

TABLE 2 f 14.73 32.05 69.71 Fno. 2.88 3.78 4.94 ω 42.31 21.60 10.35 D21.000 21.962 52.715 D9 41.120 14.134 1.000 D14 4.243 4.949 7.390 D174.647 3.942 1.500 D19 4.556 8.026 13.707 D25 2.500 10.508 21.754

Respective lens plane surfaces of the third plane, the 10-th plane, the11-th plane and the 18-th plane are constituted by a non-sphericalsurface, and non-spherical coefficients are shown in Table 3. It is tobe noted that, in the Table 3 and Tables indicating non-sphericalcoefficients, “E^(−i)” represents exponential representation having 10as base, i.e., “10^(−i)”. For example, “0.12345E-05” represents“0.12345×10⁻⁵”.

TABLE 3 PLANE No. K A⁴ A⁶ A⁸ A¹⁰ 3 0.000E+00 9.455E−06 −1.520E−081.95E−11 −1.38E−14 10 0.000E+00 −2.379E−05  −2.911E−08 −1.48E−11 −3.23E−13 11 0.000E+00 1.668E−05 −1.816E−09 3.62E−11  0.00E+00 180.000E+00 2.362E−05  7.530E−08 8.09E−10 −4.70E−12

Various aberration diagrams in the infinity far in-focus state of thenumeric value embodiment 1 are respectively shown in FIGS. 2 to 4. FIG.2 shows various aberration diagrams at the wide-angle end state(f=14.73), FIG. 3 shows various aberration diagrams at the intermediatefocal length (f=32.05) between the wide-angle end state and thetelescopic end state, and FIG. 4 shows various aberration diagrams atthe telescopic end state (f=69.71).

In the respective aberration diagrams of FIGS. 2 to 4, in the case ofspherical aberration, a ratio with respect to open F value is taken onthe ordinate and defocus is taken on the abscissa, wherein a solid lineindicates a d line, a single-dotted lines indicate C line, and dottedlines indicate spherical aberration. In the case of astigmatism, theordinate indicates image height, the abscissa indicates focus, the solidline S indicates a sagittal image surface, and dotted lines M indicatemeridional image surface. In the case of distortion aberration, theordinate indicates image height and the abscissa indicates %.

In the above-mentioned numerical value embodiment 1, as shown in theTable 13 which will be described later, the conditional formulas (1) to(8) are satisfied. Moreover, as shown in the respective aberrationdiagrams, respective aberrations are all corrected in a well balancedmanner at the wide-angle end state, the intermediate focal lengthbetween the wide-angle end state and the telescopic end state, and thetelescopic end state.

FIG. 5 shows the lens configuration by the second embodiment 2 of thezoom lens of the present invention, wherein there are arranged, in orderfrom the object side, first lens group GR1 having positive refractivepower, second lens group GR2 having negative refractive power, thirdlens group GR3 having positive refractive power, fourth lens group GR4having positive refractive power, and fifth lens group GR5 havingnegative refractive power. Further, in a magnification changing oradjusting operation from the wide-angle end state up to the telescopicend state, respective lens groups are moved on the optical axis asindicated by arrowed travel lines in FIG. 5.

The first lens group GR1 is comprised of a single lens G21 havingpositive refractive power. The second lens group GR2 is composed of anegative lens G22 having a composite non-spherical surface at the objectside, a negative lens G23, a positive lens G24, and a negative lens G25.The third lens group GR3 is composed of an iris S, a positive lens G26having non-spherical surfaces at both surfaces, and a connection lens ofa positive lens G27 and a negative lens G28. The fourth lens group GR4is composed of a positive lens G29 having non-spherical surfaces at theboth surfaces, and a connection lens of a negative lens G210 and apositive lens G211. The fifth lens group GR5 is composed of a positivelens G213 having non-spherical surface at the object side.

Values of various elements of the numerical value embodiment 2, in whichpractical numerical values are applied to the above-mentioned secondembodiment are shown in Table 4.

TABLE 4 PLANE NO. R D Nd Vd  1 79.571 5.274 1.4875 70.441  2 335.075variable  3 92.312 ASP 0.300 1.5273 42.315  4 56.834 1.800 1.8350 42.984 5 17.052 9.817  6 −88.533 1.200 1.8350 42.984  7 39.682 2.614  8 60.3273.853 1.9229 20.884  9 −82.616 1.214 10 −49.685 1.200 1.7292 54.674 11−169.164 variable IRIS INFINITY 2.000 13 23.533 ASP 4.514 1.5831 59.46014 −43.767 ASP 0.279 15 22.946 4.838 1.4970 81.608 16 −119.965 1.0001.8340 37.345 17 19.175 variable 18 19.524 ASP 7.171 1.4875 70.441 19−27.555 ASP 0.300 20 −94.179 1.200 1.8350 42.984 21 18.000 6.086 1.487570.441 22 −48.007 variable 23 −18.094 1.200 1.8042 46.503 24 −236.0680.500 25 37.222 ASP 3.500 1.8467 23.785 26 −315.162 variable 27 INFINITY2.000 1.5168 64.198 28 INFINITY 2.000 1.5523 63.424 29 INFINITY 1.000 30INFINITY 0.500 1.5567 58.649 31 INFINITY 1.000 i INFINITY 0.000

In accordance with a change of the lens position state from thewide-angle end state up to the telescopic end state, spacing D2 betweenthe first lens group GR1 and the second lens group GR2, spacing D11between the second lens group GR2 and the third lens group GR3, spacingD17 between the third lens group GR3 and the fourth lens group GR4,spacing D22 between the fourth lens group GR4 and the fifth lens groupGR5, and spacing 26 between the fifth lens group GR5 and the low-passfilter LPF are changed. In view of the above, respective values at thewide-angle end state of the respective spacings, the intermediate focallength between the wide-angle end state and the telescopic end state,and the telescopic end state are shown in Table 5 along with focallength f, F number Fno. and half picture angle ω.

TABLE 5 f 14.42 31.37 68.25 Fno. 2.85 3.65 5.03 ω 45.73 24.45 11.79 D21.200 27.771 51.410 D11 38.353 14.834 1.500 D17 17.025 15.273 9.161 D227.062 11.760 24.506 D26 5.000 16.739 27.064

Respective lens plane surfaces of the third plane, the 13-th plane, the14-th plane, the 18-th plane and the 25-th plane are each constituted bya non-spherical surface, and non-spherical coefficients are as shown inTable 6.

TABLE 6 PLANE No. K A⁴ A⁶ A⁸ A¹⁰ 3 0.000E+00 1.213E−05 −1.781E−08  2.95E−11 −2.34E−14  13 0.000E+00 −1.187E−05  2.76E−09 −6.87E−112.13E−13 14 0.000E+00 5.237E−06 6.974E−09  −7.76E−12 0.00E+00 180.000E+00 −1.161E−05  −3.59E−08   3.16E−11 −3.20E−13  19 0.000E+001.105E−05 3.13E−09  1.89E−11 0.00E+00 25   0.E+00 −1.16E−05 2.10E−08−8.05E−11 3.29E−13

Various aberration diagrams in the infinity far in-focus state of thenumerical value embodiment 2 are respectively shown in FIGS. 6 to 8.FIG. 6 shows various aberration diagrams at the wide-angle end state(f=14.42), FIG. 7 shows various aberration diagrams at the intermediatefocal length (f=31.37) between the wide-angle end state and thetelescopic end state, and FIG. 8 shows various aberration diagrams atthe telescopic end state (f=68.25).

In the respective aberration diagrams of FIGS. 6 to 8, in the case ofthe spherical aberration, a ratio with respect to an open F value istaken on the ordinate and defocus is taken on the abscissa, wherein asolid line indicates a d line, single dotted lines indicate a C line,and a dotted line indicates spherical aberration at a g line. In thecase of astigmatism, the ordinate indicates image height, the abscissaindicates focus, solid line S indicates sagittal image surface, anddotted lines M indicate meridional image surface. In the case ofdistortion aberration, the ordinate indicates image height, and theabscissa indicates %.

In the numerical value embodiment 2, as shown in FIG. 13 which will bedescribed later, the conditional formulas (1) to (8) are satisfied.Moreover, as shown in the respective aberration diagrams, respectiveaberrations are all corrected in a well-balanced manner at thewide-angle end state, the intermediate focal length between thewide-angle end state and the telescopic end state, and the telescopicend state.

FIG. 9 shows the lens configuration by the third embodiment 3 of thezoom lens of the present invention, wherein there are arranged in ordera first lens group GR1 having positive refractive power, a second lensgroup GR2 having negative refractive power, a third lens group GR3having positive refractive power, a fourth lens group GR4 havingpositive refractive power, and a fifth lens group GR5 having negativerefractive power. Further, in a magnification changing or adjustingoperation from the wide-angle end state up to the telescopic end state,respective lens groups are moved on the optical axis as indicated by anarrow solid travel line of FIG. 9.

The first lens group GR1 is comprised of single lens G31 having positiverefractive power. The second lens group GR2 is composed of a negativelens G32 having a composite non-spherical surface at the object side, anegative lens G33, a positive lens G34, and a negative lens G35. Thethird lens group GR3 is composed of an iris S, a positive lens G36having non-spherical surfaces at both its surfaces, and a connectionlens of a positive lens G37 and a negative lens G38. The fourth lensgroup GR4 is composed of a positive lens G39 having non-sphericalsurfaces at both its surfaces, and a connection lens of a negative lensG310 and a positive lens G311. The fifth lens group GR5 is composed of anegative lens G312, and a positive lens G313 having a non-sphericalsurface at the object side.

Values of various elements of the numerical value embodiment 3 in whichpractical numerical values are applied to the above-mentioned thirdembodiment are shown in Table 7.

TABLE 7 PLANE No. R D Nd Vd  1 143.348 4.5 1.6968 55.46  2 373.253variable  3 79.544 ASP 0.2 1.5273 42.315  4 48.173 1.6 1.883 40.805  519.849 11.44  6 446.917 1.2 1.835 42.984  7 27.807 8.962  8 59.203 61.9229 20.884  9 −196.687 1.641 10 −53.186 2.927 1.7725 49.624 11−200.818 variable IRIS INFINITY 2 13 24.772 ASP 6 1.4875 70.441 14−37.719 ASP 1 15 27.651 6 1.497 81.608 16 −319.491 1 1.834 37.345 1722.57 variable 18 18.223 ASP 6.888 1.5247 56.238 19 −26.379 ASP 0.8 20−50.637 1.2 1.883 40.805 21 15 6.84 1.4875 70.441 22 −35.587 variable 23−19.062 1.2 1.8042 46.503 24 −80 0.5 25 55.153 ASP 3 1.8467 23.785 26−253.322 variable 27 INFINITY 2 1.5168 64.198 28 INFINITY 2 1.552363.424 29 INFINITY 1 30 INFINITY 0.5 1.5567 58.649 31 INFINITY 1 iINFINITY 0

In accordance with a change of the lens position state from thewide-angle end state up to the lens position state, a spacing D2 betweenthe first lens group GR1 and the second lens group GR2, spacing D11between the second lens group GR2 and the third lens group GR3, spacingD17 between the third lens group GR3 and the fourth lens group GR4,spacing D22 between the fourth lens group GR4 and the fifth lens groupGR5, and spacing D26 between the fifth lens group GR5 and the low-passfilter LPF are changed. In view of the above, various values at thewide-angle end state of the respective spacings, the intermediate focallength between the wide-angle end state and the telescopic end state,and the telescopic end state are shown in Table 8 along with focallength f, F number Fno. and half picture angle ω.

TABLE 8 f 12.10 24.20 48.40 Fno. 2.85 3.66 5.03 ω 49.81 30.18 16.33 D21.000 25.829 52.000 D11 44.445 16.793 1.000 D17 11.498 9.507 5.693 D229.853 13.825 25.064 D26 2.000 11.681 20.788

Respective lens plane surfaces of the third plane, the 13-th plane, the14-th plane, the 18-th plane, the 19-th plane and the 25-th plane areconstituted by non-spherical surfaces. Non-spherical coefficients are asshown in Table 9.

TABLE 9 PLANE No. K A⁴ A⁶ A⁸ A¹⁰ 3 0.000E+00  1.02E−05 −8.79E−09 1.03E−11 −3.46E−15  13 0.000E+00 −1.22E−05  1.66E−08 −2.43E−10 1.31E−1214 0.000E+00  7.35E−06  2.51E−08 −2.59E−10 1.48E−12 18 0.000E+00−7.12E−06 −2.49E−08  4.13E−11 −5.99E−13  19 0.000E+00  1.94E−05−7.46E−09  7.91E−12 9.22E−14 25 0.000E+00 −1.66E−06 2.72E−08 −2.26E−107.31E−13

Various aberration diagrams in the infinity far in-focus state of thenumerical value embodiment 3 are respectively shown in FIGS. 10 to 12,wherein FIG. 10 shows various aberration diagrams at the wide-angle endstate (f=12.10), FIG. 11 shows various aberration diagrams at theintermediate focal length (f=24.20) between the wide-angle end state andthe telescopic end state, and FIG. 12 shows various aberration diagramsat the telescopic end state (f=48.40).

In the respective aberration diagrams of FIGS. 10 to 12, in the case ofspherical aberration, a ratio with respect to an open F value is takenon the ordinate, and defocus is taken on the abscissa, wherein solidline indicates spherical aberration at a d line, single dotted linesindicate spherical aberration at a C line, and a dotted line indicatesspherical aberration at a g line. In the case of astigmatism, theordinate indicates image height, the abscissa indicates focus, solidline S indicates a sagittal image surface, and dotted lines M indicatemeridional image surface. In the case of distortion aberration, theordinate indicates image height, and the abscissa indicates %.

In the numerical value embodiment 3, as shown in the Table 13 which willbe described later, the conditional formulas (1) to (8) are satisfied.Moreover, as shown in the respective aberration diagrams, respectiveaberrations are corrected in a well-balanced manner at the wide-angleend state, the intermediate focal length between the wide-angle endstate and the telescopic end state, and the telescopic end state.

FIG. 13 shows the lens configuration by the fourth embodiment 4 of thezoom lens of the present invention, wherein there are arranged, in orderfrom the object side, a first lens group GR1 having positive refractivepower, second lens group GR2 having negative refractive power, thirdlens group GR3 having positive refractive power, fourth lens group GR4having negative refractive power, fifth lens group GR5 having positiverefractive power, and a sixth lens group GR6 having negative refractivepower. Further, in a magnification changing or adjusting operation fromthe wide-angle end state up to the telescopic end state, the respectivelens groups are moved on the optical axis as indicated by arrowed solidtravel line in FIG. 13.

The first lens group is comprised of a single lens G41 having positiverefractive power. The second lens group GR2 is composed of a negativelens G42 having a non-spherical surface at the object side, a negativelens G43 having a composite non-spherical surface at the image pick-upsurface side, and a positive lens G44. The third lens group GR3 iscomposed of a positive lens G45 having a composite non-spherical surfaceat the object side, an iris S, and a connection lens of a negative lensG46 and a positive lens G47 having non-spherical surfaces at the imagepick-up surface side. The fourth lens group GR4 is comprised of anegative lens G48. The fifth lens group GR5 is comprised of a positivelens G49 having non-spherical surfaces at both surface sides. The sixthlens group GR6 is composed of a connection lens of a negative lens G410and a positive lens G411, and a positive lens G412.

Values of various elements of the numerical value embodiment 4 in whichpractical numerical values are applied to the above-mentioned fourthembodiment are shown in Table 10.

TABLE 10 PLANE No. R D Nd Vd  1 59.370 9.000 1.6180 63.396  2 260.955variable  3 133.403 ASP 2.000 1.8350 42.984  4 17.570 6.501  5 472.3031.700 1.8350 42.984  6 45.831 0.200 1.5361 41.207  7 34.599 ASP 3.013  849.990 4.185 1.9229 20.880  9 5000.000 variable 10 19.172 ASP 0.2001.5146 49.961 11 19.221 4.635 1.4875 70.441 12 −300.000 5.000 IRISINFINITY 3.250 14 20.595 0.900 1.9037 31.312 15 11.395 4.368 1.623058.122 16 −60.206 ASP variable 17 −167.453 1.000 1.9037 31.319 18 24.684variable 19 50.507 ASP 2.400 1.5831 59.461 20 −51.079 ASP variable 21−13.347 1.800 1.8830 40.805 22 −5000.000 3.275 1.8467 23.785 23 −36.8451.000 24 45.259 3.088 1.9229 20.880 25 −500.000 variable 26 INFINITY2.010 1.5523 63.424 27 INFINITY 2.100 28 INFINITY 0.500 1.5567 58.649 29INFINITY 1.000 i INFINITY 0.000

In accordance with a change of the lens position state from the broadangle state up to the telescopic end state, a spacing D2 between thefirst lens group GR1 and the second lens group GR2, spacing D9 betweenthe second lens group GR2 and the third lens group GR3, spacing D16between the third lens group GR3 and the fourth lens group GR4, spacingD18 between the fourth lens group GR4 and the fifth lens group GR5,spacing D20 between the fifth lens group GR5 and the sixth lens groupGR6, and spacing D25 between the sixth lens group GR6 and the low-passfilter LPF are changed. In view of the above, various values at thewide-angle end state of the respective spacings, the intermediate focallength between the wide-angle end state and the telescopic end state,and the telescopic end state are shown in Table 11 along with focallength f, F number Fno. and half picture angle ω.

TABLE 11 f 20.00 41.95 88.00 Fno. 2.89 3.52 4.66 ω 33.14 17.10 8.49 D23.447 24.779 43.000 D9 38.000 15.015 1.000 D16 4.372 4.221 2.000 D183.181 3.332 5.553 D20 7.887 10.468 18.215 D25 2.000 8.255 16.076

Respective lens plane surfaces of the third plane, the 7-th plane, the10-th plane, the 16-th plane, the 19-th plane and the 20-th plane areconstituted by non-spherical surfaces. Non-spherical coefficients are asshown in Table 12.

TABLE 12 PLANE No. K A⁴ A⁶ A⁸ A¹⁰ 3 0.000E+00 −7.08E−08 −1.98E−10−3.45E−12 −1.17E−15 7 −1.092E−01  −1.09E−05 −4.70E−08  1.86E−10−8.70E−13 10 0.000E+00 −1.41E−05 −2.15E−08 −1.68E−10  7.12E−13 162.549E−01  2.68E−05 −1.25E−07  7.04E−10 −5.36E−12 19 0.000E+00  7.99E−052.45E−07 −1.77E−10  5.78E−11 20 0.000E+00  4.90E−05 3.26E−07 −8.57E−107.3256E−11 

Various aberration diagrams in the infinity far in-focus state of thenumerical value embodiment 4 are respectively shown in FIGS. 14 to 16,wherein FIG. 14 shows various aberration diagrams at the wide-angle endstate (f=20.00), FIG. 15 shows various aberration diagrams at theintermediate focal length (f=41.95) between the wide-angle end state andthe telescopic end state, and FIG. 16 shows various aberration diagramsat the telescopic end state (f=88.00).

In the respective aberration diagrams of FIGS. 14 to 16, in the case ofthe spherical aberration, a ratio with respect to an open F value istaken on the ordinate and defocus is taken on the abscissa, wherein asolid line indicates spherical aberration at a d line, single dottedlines indicate spherical aberration at a C line, and dotted linesindicate spherical aberration at a g line. In the case of astigmatism,the ordinate indicates image height, the abscissa indicates focus, solidline S indicates a sagittal image surface, and dotted lines indicatemeridional image surfaces. In the case of distortion aberration, theordinate indicates image height, and the abscissa indicates %.

In the numerical value embodiment 4, as shown in the Table 13 which willbe described later, the conditional formulas (1) to (8) are satisfied.Moreover, respective aberrations are all corrected in a well-balancedmanner at the wide-angle end state, the intermediate focal lengthbetween the wide-angle end state and the telescopic end state, and thetelescopic end state.

TABLE 13 Numeric Conditional Formula Value (1) (2) (3) (4) (5)Embodiment YMAX/Fw VdG1 F1/√Fw · FT BGRRT Twbf/fw 1 0.874 70.441 5.0761.533 0.452 2 0.985 70.441 6.754 1.586 0.688 3 1.174 55.460 13.838 1.3920.573 4 0.650 63.396 2.904 1.483 0.336 Numeric Conditional Formula Value(6) (7) (8) Embodiment VdGRRn VdGRRp |F2/√Fw · FT| VdGR3p 1 37.345120.8835 0.723 59.460 2 46.5025 23.7848 0.593 70.534 3 46.5025 23.78480.820 76.025 4 40.8054 20.8804 0.598 64.282

It is to be noted that while respective lens groups of zoom lenses shownin the respective embodiments are constituted only by a refraction typelens for deflecting rays of incident light by refraction (i.e., lens ofthe type in which deflection is performed at the interface or surfacebetween media having different refractive indices), respective lensgroups may be constituted, without being limited to the above mentionedimplementation, by, e.g., a diffraction type lens for deflecting rays ofincident light by refraction, refraction-diffraction hybrid type lensfor deflecting rays of incident light by a combination of diffractingaction and refracting action, and/or refractive index distribution typelens for deflecting rays of incident light by refractive indexdistribution within a medium, etc.

Moreover, a plane having no optical power (e.g., a reflection planesurface, refraction plane surface, diffraction plane surface) may beprovided within an optical path to bend or fold the optical path beforeand after the zoom lens or in the middle thereof. A bending position maybe set as occasion demands. By suitable bending of optical path, it ispossible to attain realization of a superficial thin structure ofcamera.

Moreover, one or plural lens groups, or a portion of one lens group maybe shifted in a direction substantially perpendicular to the opticalaxis among the lens groups constituting the zoom lens to thereby haveability to shift image. A detection system for detecting vibration ormovement of the camera, a drive system for shifting the lens group, anda control system for giving shift quantity to the drive system inaccordance with an output of the detection system may be combined tohave thereby an ability to allow such combined system to function as avibration proof optical system.

The embodiment of the image pick-up apparatus of the present inventionis shown in FIG. 17.

The image pick-up apparatus 10 comprises a zoom lens 20, and includes animage pick-up device 30 for converting an optical image formed by thezoom lens 20 into an electric signal. In this example, as the imagepick-up device 30, there can be applied photo-electric convertingdevices using, e.g., CCD (Charge Coupled Device) or CMOS (ComplementaryMetal-Oxide Semiconductor), etc. The zoom lens according to the presentinvention can be applied to the zoom lens 20. In FIG. 17, respectivelens groups of the zoom lens 1 according to the first embodiment shownin FIG. 1 are illustrated as a single lens in a simplified manner. It isa matter of course that not only the zoom lens according to the firstembodiment, but also the zoom lenses according to the second and thirdembodiments and/or the zoom lens of the present invention constituted bythe embodiments except for the embodiments shown in this specificationmay be used.

An electric signal formed by the image pick-up device 30 is separated bya video separation circuit 40. Thus, a focus control signal is sent to acontrol circuit 50, and a video signal is sent to a video processingcircuit. The signal which has been sent to the video processing circuitis processed so as to take a form suitable for processing subsequentthereto. The processed signal thus obtained is caused to undergo variousprocessing such as display by a display unit, recording onto recordingmedium and/or transfer by communication means, etc.

The control circuit 50 is supplied with an operation signal from theexternal, e.g., operation of zoom button, etc. so that variousprocessings are performed in accordance with the operation signal. Forexample, when a focus command by the zoom button is inputted, a driveunit 70 is caused to become operative through a drive circuit 60 inorder that there results a focal length state based on the command tomove the respective lens groups to a predetermined position. Positioninformation of the respective lens groups which have been obtained byrespective sensors 80 are inputted to the control circuit 50. Theposition information thus inputted is referred in outputting a commandsignal to the driver circuit 60. Moreover, the control circuit 50 servesto check a focus state on the basis of a signal sent from the videoseparation circuit 40 to conduct a control such that that optimum focusstate can be obtained.

The above-mentioned image pick-up apparatus 10 may take various forms aspractical products. For example, the image pick-up apparatus 10 can bewidely applied as a camera unit, etc. of digital input/output equipmentsuch as a digital still camera, digital video camera, mobile telephonein which camera is assembled or incorporated and/or PDA (PersonalDigital Assistant) in which a camera is assembled or incorporated, etc.

It is to be noted that all of the practical shapes and numerical valuesof respective components shown in the above-described respectiveembodiments and numeric embodiments only illustrate mere examples ofembodiments in carrying out the present invention, and technical fieldof the present invention should not be restrictively interpreted bythose implementations.

INDUSTRIAL APPLICABILITY

It is possible to provide a zoom lens including a broad picture angle of60 to 100 degrees as a photographic picture angle of the wide-angle endstate, and having the magnification ratio of about three times to sixtimes, small front gem diameter, excellent compactness and high imageformation performance, and image pick-up apparatus using such zoom lenssystem. The zoom lens and the image pick-up apparatus using such zoomlens can be widely utilized for digital video camera and/or digitalstill camera, etc.

1. A zoom lens consisting of plural groups and serving to change groupspacing or spacings to thereby perform magnification changing oradjusting operation, the zoom lens comprising a first lens group GR1having positive refractive power, a second lens group GR2 havingnegative refractive power and a third lens group GR3 having positiverefractive power which are arranged in order from the object side, and alast lens group GRR arranged at the side closest to image surface andhaving negative refractive power, wherein the first lens group GR1 isconstituted by single positive lens, and satisfies the followingconditional formulas (1), (2)0.5<Ymax/FW<1.3  (1)VdG1>40  (2) wherein in the above formulas, Ymax: maximum image heighton an image pick-up surface; FW: focal length at the wide-angle endstate of the entire lens system; and VdG1: Abbe number at d line of thefirst lens group GR1, wherein the first lens group GR1 satisfies thefollowing conditional formula (3)2<F1/√FW·FT<15  (3) wherein in the above formula, F1: focal length ofthe first lens group GR1; FT: focal length at the telescopic end stateof the entire lens system; and √FW·FT: square root of product of FW andFT and wherein the last lens group GRR includes a negative lens GRn atthe side closest to the object, and a positive lens GRp at the sideclosest to the image surface, and satisfies the following conditionalformulas (4), (5) and (6)1.2<βGRRT<1.8  (4)0.2<Twbf/FW<1.2  (5)VdGRRn>VdGRRp  (6) wherein in the above formulas, βGRRT: magnificationat the telescopic end state of the last lens group GRR; Twbf: back focus(air conversion length) at the wide-angle end state; VdGRRn: Abbe numberat a d line of the negative lens GRn; and VdGRRp: Abbe number at a dline of the positive lens GRp.
 2. The zoom lens according to claim 1,wherein at least one lens plane surface of the second lens group GR2 isconstituted by a non-spherical surface, and the second lens group GR2satisfies the following conditional formula (7)0.4<|F2/√FW·FT|<1.0  (7) wherein in the above formula, F2: focal lengthof the second lens group GR2.
 3. The zoom lens according to claim 1,wherein the third lens group GR3 at least includes one positive lens,and one negative lens, at least one lens plane surface of the respectivelens plane surfaces is constituted by a non-spherical surface, and thethird lens group GR3 satisfies the following conditional formula (8)VdGR3p>50  (8) wherein in the above formula, VdGR3 p: average value ofAbbe numbers at a d line of the positive lens within the third lensgroup GR3.
 4. An image pick-up apparatus comprising a zoom lensconsisting of plural groups and serving to change group spacing orspacings to thereby perform magnification changing or adjustingoperation, and an image pick-up device for converting an optical imageformed by the zoom lens into an electric signal, wherein the zoom lenscomprises a first lens GR1 having positive refractive power, a secondlens group GR2 having negative refractive power and a third lens groupGR3 having positive refractive power which are arranged in order fromthe object side, and a last lens group GRR arranged at the side closestto the image surface and having negative refractive power, and the firstlens group GR1 is constituted by single positive lens, and satisfies thefollowing conditional formulas (9), (10)0.5<Ymax/Fw<1.3  (9)VdG1>40  (10) wherein in the above formula, Ymax: maximum image heighton image pick-up surfaces FW: focal length at the wide-angle end stateof the lens entire system; and VdG1: Abbe number at a d line of thefirst lens group GR1, wherein the first lens group GR1 satisfies thefollowing conditional formula (11)2<F1/√FW·FT<15  (11) wherein in the above formula F1: focal length ofthe first lens group GR1 FT: focal length at the telescopic end state ofthe entire lens system; and √FW·FT: square root of product of FW and FT,and wherein the last lens group GRR includes a negative lens GRn at theside closest to the object, and a positive lens GRp at the side closestto the image surface, and satisfies the following conditional formulas(12), (13) and (14)1.2<βGRRT<1.8  (12)0.2<Twbf/FW<1.2  (13)VdGRRn>VdGRRp  (14) wherein in the above formula βGRRT: magnification atthe telescopic end state of the last lens group GRR; Twbf: back focus(air conversion length) at the wide-angle end state VdGRRn: Abbe numberat d line of the negative lens GRn; and VdGRRp: Abbe number at d line ofthe positive lens GRp.
 5. The image pick-up apparatus according to claim4, wherein at least one lens plane surface of the second lens group GR2is constituted by non-spherical surface, and the second lens group GR2satisfies the following conditional formula (15)0.4<|F2/√FW·FT|<1.0  (15) wherein in the above formula, F2: focal lengthof the second lens group GR2.
 6. The image pick-up apparatus accordingto claim 4, wherein the third lens group GR3 at least includes onepositive lens and one negative lens, at least one lens plane surface ofthe respective lens plane surfaces is constituted by a non-sphericalsurface, and the third lens group GR3 satisfies the followingconditional formula (16)VdGR3p>50  (16) wherein in the above formula, VdGR3 p: average value ofAbbe numbers at d line of the positive lens within the third lens groupGR3.